With the maturity of automatic sheet feeding technologies, automatic sheet feeding apparatus are widely used in a diversity of document processing machines such as printers, copiers and multifunction peripherals. The automatic sheet feeding apparatus are used for successively feeding a stack of documents into the inner portion of the document processing machine so as to implement associated operations and achieve the labor-saving purpose.
FIG. 1 is a schematic view illustrating a conventional automatic sheet feeding apparatus. As shown in FIG. 1, the automatic sheet feeding apparatus 1 comprises a sheet pick-up roller 10, a sheet separation roller 11, a sheet separation slice 12 and a sheet feeding channel 13. The sheet separation roller 11 is sheathed around a driving shaft 14. As such, upon rotation of the driving shaft 14, the sheet separation roller 11 is simultaneously rotated. For feeding a document by the automatic sheet feeding apparatus 1, the document should be fed into a sheet entrance 16 by the sheet pick-up roller 10 and then transported to the sheet separation roller 11. The sheet separation roller 11 and the sheet separation slice 12 collectively offer a friction force on the document, so that only one document is allowed to be fed into the sheet feeding channel 13 for each time. Regardless of which kind of automatic sheet feeding apparatus is used, the document is readily jammed by using the sheet pick-up roller to feed the document. In a case that the evenness of the sheet-like document is insufficient, or in another case that too many documents are simultaneously fed by the sheet pick-up roller 10 to result in a double feeding problem, the possibility of getting jam of the document in the region between the sheet separation roller 11 and the sheet separation slice 12 is largely increased. Since the document is securely held between the sheet separation roller 11 and the sheet separation slice 12, the jammed document is not easily pulled out. If the jammed document is directly pulled out by exerting a pulling force on the document, the automatic sheet feeding apparatus 1 is readily suffered from a breakdown or the document is possibly broken.
For solving these drawbacks, the conventional automatic sheet feeding apparatus 1 usually has an additional sheet releasing mechanism. In a case that the automatic sheet feeding apparatus 1 is suffered from the jamming problem, the user may control the sheet releasing mechanism to shift the axle center of driving shaft 14 from the position A to the position B. As a consequence, the sheet separation roller 11, which is mounted on the driving shaft 14, is also deviated from its original axle center and no longer in close contact with the jammed document. Under this circumstance, the user may pull out the jammed document between the sheet separation roller 11 and the sheet separation slice 12. An automatic sheet feeding apparatus having a sheet releasing mechanism is disclosed in for example Taiwanese Patent Publication No. I303608.
FIG. 2 is a schematic exploded view illustrating a sheet releasing mechanism disclosed in Taiwanese Patent Publication No. I303608. As shown in FIG. 2, the sheet releasing mechanism 2 comprises a base 20 and a control lever 21. The control lever 21 comprises a pivotal part 211, a collar 212 and a handle part 213. The collar 212 is arranged between the pivotal part 211 and the handle part 213. The pivotal part 211 is substantially a cylindrical post serving as a rotating shaft of the control lever 21. The collar 212 is substantially a circular channel sheathed around the driving shaft 14 of an automatic sheet feeding apparatus 1 (see FIG. 1).
FIGS. 3A and 3B are schematic views illustrating a process of removing a jammed document by using the sheet releasing mechanism disclosed in Taiwanese Patent Publication No. I303608. For positioning the sheet releasing mechanism 2, the control lever 21 and the base 20 comprise a salient 214 and an indentation 201, respectively. When the salient 214 is engaged with the indentation 201, the control lever 21 is fixed onto the base 20. During normal feeding operation of the automatic sheet feeding apparatus 1, the engagement of the salient 214 and the indentation 201 prevents the control lever 21 from being rotated with respect to the base 20. Under this circumstance, the operation of the driving shaft 14 is not influenced by the control lever 21. In a case that the automatic sheet feeding apparatus 1 has a jamming problem, the user could stir the control lever 21 in the direction indicated by the arrow D (as shown in FIG. 3A), so that the salient 214 is disengaged from the indentation 201. Next, the user could stir the handle part 213 of the control lever 21 in the direction indicated by the arrow C (as shown in FIG. 3B) in order to rotate the collar 212 of the control lever 21. As a consequence, the sheet separation roller 11, which is mounted on the driving shaft 14, is deviated from its original axle center and no longer presses the jammed document.
Since the sheet releasing mechanism 2 has no additional structure for fixing the control lever 21 after the salient 214 of the control lever 21 is disengaged from the indentation 201, the control lever 21 is readily rocked back and forth. The rocking condition of the control lever 21 is troublesome during the process of pulling out the jammed document.